testrunner:
- add option to launch a experimental test run, which will include all
tests including those which havent been added to the normal test plan
yet.
- this can be triggered by typing "experimental" or "exp" instead
of a filename.
runner.t:
- create experimental test plan if experimental arg is used.
Change-Id: I921664addbc0fa5c06c5d1a619baec82590eb8c0